breathalyzer isn’t going to give them the answer they’re looking for. There’s no roadside test for THC intoxication that works the way a breath test works for alcohol. Instead, law enforcement frequently turns to a Drug Recognition Evaluator, a specially trained officer who conducts a structured evaluation designed to determine whether someone is under the influence of a specific drug category.
What a DRE Evaluation Involves
The Drug Recognition Evaluator protocol, developed by the International Association of Chiefs of Police, consists of a 12-step evaluation process conducted after an initial arrest or detention. The steps include:
- Breath alcohol test to rule out alcohol as the primary cause of observed impairment
- Interview of the arresting officer
- Preliminary examination including pulse rate, pupil size, and eye tracking
- Dark room examination of pupil dilation under varying light conditions
- Vital signs assessment including blood pressure, temperature, and pulse
- Examination of muscle tone and injection sites
- Statements from the subject and a final opinion
At the end of this process, the DRE gives an opinion about whether the driver is impaired and, if so, which category of drug they believe is responsible. Cannabis is one of the seven drug categories the protocol covers.
Why DRE Evidence Can Be Challenged
DRE testimony has been contested in courts across the country, and for good reason. The evaluation is built on a combination of physiological observations and subjective judgment. Several of its components involve factors that vary significantly between individuals regardless of drug use, including pupil size, pulse rate, and muscle tone.
Minnesota does not have a per se legal limit for THC concentration the way it does for alcohol. This means there’s no number a blood test produces that automatically establishes impairment. The prosecution instead relies heavily on the DRE’s opinion, which is itself grounded in an evaluation that has known limitations.
A Brooklyn Park marijuana DWI lawyer can examine the DRE’s training records, the specific conditions under which the evaluation was conducted, whether the protocol was followed correctly, and whether the officer’s conclusions are supported by the physical findings documented in the evaluation report.
How Blood Tests Interact With DRE Opinions
After a DRE evaluation, law enforcement typically seeks a blood draw to detect THC and its metabolites. Here the complexity deepens. THC metabolites remain detectable in blood long after any impairment has passed. A positive blood test doesn’t establish that the driver was impaired at the time of driving. The DRE’s opinion and the blood test results together form the prosecution’s case, but neither alone is definitive.
Challenging the connection between the observed evaluation results, the blood test findings, and actual impairment at the time of the stop is a central component of marijuana DWI defense in Minnesota.
What to Do After a Marijuana DWI Arrest
Acting quickly matters. The window to challenge license revocation is limited, and the evidence from the DRE evaluation and blood draw needs to be examined before the case develops further on its own momentum.
Archambault Criminal Defense represents clients facing marijuana DWI charges throughout Minnesota, including cases where DRE evaluations form the core of the prosecution’s evidence.
If you were charged with a marijuana DWI in Minnesota and a Drug Recognition Evaluator was involved, speaking with a Brooklyn Park marijuana DWI lawyer as soon as possible gives your defense the best opportunity to identify weaknesses in the state’s case before the hearing.
